Powertrain Control Module (PCM) - 66RFE
P0735-GEAR RATIO ERROR IN 5TH
For a complete wiring diagram, refer to the Wiring Information
Theory of Operation
The transmission system uses two speed sensors, one to measure input rpm and one to measure output rpm. These inputs are essential for proper transmission operation. Therefore the integrity of this data is verified through the following checks:
NOTE: Various Gear Ratio Error DTCs will set only if the transmission slips after first achieving the correct ratio. Therefore a transmission with no drive (or reverse) may not set any Gear Ratio Error DTC because it never achieves a correct gear ratio.
1) Once in a particular gear, if the gear ratio varies from the correct gear ratio the corresponding in-gear DTCs P0729 and P0731-36 is set.
2) An excessive change in input or output speeds indicating an intermittent signal which results in DTCs P0716 and/or P0721 setting.
3) If the common speed sensor ground circuit is lost, both sensor inputs read the pulses from the input speed sensor when at a stop in neutral. Since the input speed sensor reads 60 teeth from the input clutch hub and the output speed sensor reads 30 teeth from the park gear, the result is an apparent speed ratio of 1:2 and may cause DTC P1794 to set.
- When Monitored:
Continuously with the ignition on, engine running and after the transmission achieves the correct gear ratio.
- Set Condition:
If the ratio of the Input rpm to the Output rpm does not match the current gear ratio then DTC P0735 will set. This DTC can take up to five minutes of problem identification before illuminating the MIL.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.
1. CHECK FOR RELATED DTCs
1. With the scan tool, check for other transmission DTCs
2. If any of these DTCs are present, perform their respective tests first.
Are any Transmission solenoid, line pressure, speed sensor and/or loss of prime DTCs present?
Yes
- If these DTCs are present they may cause a Speed Ratio Error. Perform the test for P0944 first if it is present. P0944
No
- Go To 2
2. CHECK THE EVENT DATA
1. With the scan tool, read and record the Event Data.
NOTE: Make sure to record all Event Data stored in the scan tool for future reference in this test procedure.
Does the Event Data display information for DTC P0735?
Yes
- Go To 4
No
- Go To 3
3. CHECK FOR ANOTHER DTC
In the Event Data recorded earlier, does the Event Data show DTC P1790 with Target Gear = 5th or with both the 4C and OD clutches applying?
Yes
- Go To 4
No
- Go To 6
4. CHECK THE INPUT RPM
In the Event Data recorded earlier, does the Input rpm read zero?
Yes
- P0716 Perform the diagnostic procedure for P0716-Input Speed Sensor Circuit Performance. Diagnose the DTC as if it is set and current.
No
- Go To 5
5. CHECK THE LINE PRESSURE READING
In the Event Data recorded earlier, is the line pressure reading more than 10 psi below the desired line pressure reading?
Yes
- Remove the Transmission Oil pan and check the Transmission Oil filter for improper installation or plugged. If the Primary oil filter is OK, check the main regulator valve in pump. If excessive debris is in the oil pan, check clutches and repair as necessary. Refer to the proper repair procedures.
- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test
No
- Go To 6
6. CHECK TRANSMISSION FOR SLIPPAGE
1. Erase DTCs and road test the vehicle.
2. Check the transmission operation in forward and reverse gears.
During the road test, was there obvious slippage noted in any gear?
Yes
- Go To 8
No
- Go To 7
7. CHECK IF THE DTC RESETS
1. With the scan tool, check for transmission DTCs after the road test.
Did DTC P0735 reset?
Yes
- Go To 8
No
- Test Complete.
8. CHECK INTERNAL TRANSMISSION
1. Remove the Transmission Oil Pan and Valve Body and check for the following:
- Excessive debris in the oil pan.
- Remove the Valve Body and check if the accumulator cover is intact and the 4C tower seal is not cut or split.
- OD and 4C accumulator pistons for cracks and/or cut seals.
- Solenoid Switch Valve and its plugs for stickiness or wear.
- Cut or missing No. 5 and/or No. 6 check ball.
- OD bleed orifice (on top of the main valve body) is intact.
- Air check the OD and 4C hydraulic clutch circuits for excessive leakage.
NOTE: Both the OD and 4C hydraulic clutch circuits contain a small bleed orifice. A small amount of air leakage is considered normal. The OD hydraulic clutch circuit bleed orifice connects to the Reverse input clutch hydraulic cavity. A small amount of air leakage into the Reverse hydraulic clutch circuit is considered normal.
Were any problems found?
Yes
- Repair as necessary. Refer to the proper repair procedures.
NOTE: If the OD or 4C clutch has failed but no obvious cause is found (such as a cut piston seal, broken seal ring, stuck regulator valve or any other items listed above) replace the Transmission Solenoid/TRS Assembly in addition to any necessary internal repairs.
- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test
No
- Go To 9
9. CHECK ROAD TEST RESULTS
Perform the appropriate action for the condition(s) which best describe the road test results:
1st gear was OK. Slipped in 2nd (or failed to make the 1-2 upshift and went into Limp-in) and slipped in Reverse
- Go To 10
1st and 2nd gears were OK. Slipped in 3rd gear AND in Reverse
- Remove the Transmission. Inspect the reaction annulus gear weld to the reverse carrier and the reaction sun gear weld to the 4C clutch hub and repair as necessary.
- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test
1st and 2nd gears were OK. Slipped in 3rd gear but NOT in Reverse.
- Replace Transmission Solenoid/TRS Assembly and Perform 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test If a continued Slippage is noted in 3rd gear during the Verification test, Remove the Transmission and inspect the 4C clutch and repair as necessary.
1st through 3rd gears were OK. Slipped in 4th, 5th or 6th gear. Reverse was OK
- Go To 11
10. CHECK FOR FAILED REVERSE GEARSET SPLINES
Working through the windows in the bottom of the case, check for a failed Reverse Sun or Annulus gear spline as follows:
1. Hold the Transmission Output Shaft by holding the Transmission Manual Lever in the park position.
2. Apply the 4C clutch using 30-40 psi shop air at the apply port in the center bulkhead. .
3. Attempt to rotate the input annulus gear and drive shell (the drum that encloses the two rearmost gearsets).
NOTE: Due to the overrunning clutch, the gear and drive shell normally rotates in one direction only.
Can the drive shell be rotated?
Yes
- Repair internal transmission as necessary. Check the reverse annulus gear spline to the input carrier, and the reverse sun gear spline to the reaction carrier hub.
- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test
No
- Replace the Transmission Solenoid/TRS Assembly.
- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test
11. CHECK THE OD SHAFT AND REVERSE CARRIER SPLINE
1. Remove the Transmission and inspect the OD shaft and its spline to the reverse carrier hub.
Were any problems found?
Yes
- Repair as necessary. Refer to the proper repair procedures.
- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test
No
- Disassemble and inspect the input clutch assembly. Check the OD and Reverse clutch seals, discs and bleed orifice (in the OD/Reverse clutch piston) and repair as necessary.
NOTE: If the OD clutch has failed but no obvious cause is found (such as a cut piston seal, broken seal ring, stuck regulator valve, etc.) replace the Transmission Solenoid/TRS Assembly in addition to any other necessary repairs.
- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test